Automatic measuring and printing apparatus



AUTOMATIC MEASURING AND PRINTING APPARATUS Filed May 25, 1953 5 Sheets-Sheet l 9 i l l I I O d 4/ Invenlors:

A Home y Nov. 6, 1 56 s. G. MEADOWS ET AL 2,769,958

AUTOMATIC MEASURING AND PRINTING APPARATUS Filed May 25, 1953 5 SheetsShee 2 fi Inventorsl g M IMZWM y Attorney Nov. 6, 1956 ,s. G. MEADOWS ETAL AUTOMATIC MEASURING AND PRINTING APPARATUS 5 Sheets-Sheet 5 Filed May 25, 19

Inventors;

. M Att 1956 s. G. MEADOWS ET AL 2,769,958

AUTOMATIC MEASURING AND PRINTING APPARATUS Filed May 25, 1953 s Sheets-Sheet 4 I I l a I a I. n E n J Bhl J52 m an El 'aaa l Inventors- 7 MLWZMM By WM M Attorney Nov. 6, 1956 s, MEA DOWS ETAL 2,769,958

AUTOMATIC MEASURING AND PRINTING APPARATUS Filed May 25, 1953 5 Sheets-Sheet 5 United States Patent AUTOMATIC MEASURING AND APPARATUS Application May 25, 1953, Serial No. 356,972 8 Claims. (Cl. 324-73) PRINTING This invention ing and means of marking points or lines of a chart but provides for the printing of the readings by means of type on a record sheet. The result attained in this recording is the production of columns of figures with or without signs typed in appropriate positions on the record sheet.

The term reading is used herein as indicating a value to which an instrument (or group of instruments) is set. It is possible that the instrument may be such that a visual indication is given so that an actual reading can be taken. In many cases, however, this will not be so and it is not necessary for the operation of the invention.

step-by-step across the sheet (spacing movement).

The electro-mechanical control device for operating a type may consist of an electro-magnet, the armature of which is attached to the lever at which the typed matter appears. The first of said switching devices provides circuit connections for printing switching devices to cause the actuation of a type member appropriate for printing a part of the reading at the correct position on the record sheet.

One example of a recording to which the invention can be applied is the testing of the tain of their electrical properties, such as capacities, resistances and standard of or integrity of insulation. These require for each quad the taking of a number of readings in appropriate sequence and the recordings of these readings in one line for each quad extending across the sheet so that the respective readings appear in their appropriate columns.

In accordance with the present invention the first of represented by a set of relays arranged to act in sequence and in steps to add to or subtract from the impedance of a testing bridge or other measuring device until a balance is reached, each addition or subtraction being accompanied by the setting up, by means of relay contacts, of a circuit for an electro-magnet or for electro-magnets which actuate the type of the printing device. The circuits so set up co-act with circuits established by a position switch actuated by the movement of the record carrier.

The printing circuits which relays are held until the said switching devices is their starting condition switch.

Each relay may be considered in three functional aspects. The first relates to coil circuit.

by the movement of the position range of operation between the maximum and minimum can be attained by steps of unit value. Binary or other combinations of figures, however, can be used in place of a decade system if required.

For operation in a decade system there will be a set of nine relays for the unit steps, followed by a relay or relay group which transfers between the units and tens and a set of tens relays to the number required. If this number is nine it may be followed by one or more hundred relays. The transfer arrangement between adjacent denominations (units and tens or tens and hundreds) is so arranged that at transfer all the relays in the lower denomination are cleared, that is returned to their initial condition.

An advantage of this relay arrangement is that a single set of relays can serve for adjusting two or more kinds of quantities, such, for instance, as capacity and resistance, by a simple switching arrangement, thus enlarging the scope of the testing apparatus in a very simple manner.

In the printing arrangement an electro-rnagnet for each of the numerals required (usually 0, 1, 2, 3, 4, 5, 6, 7, 8, 9) is provided together with the signs plus and minus where a distinction has to be made between the positive and negative quantities. The circuit for each or" the numeral magnets is controlled by a relay in each denomination (units, tens, hundreds) to the upper limit required, these circuits being set by the relays to the result arrived at when adjustment of relays is stopped at the balance of the testing device. The association selecting effect of the in front of a numeral of one, two or three the co-operation of the relays and the position They can be made to repeat their operations so that a series of tests follow one after the other and the results are printed in columns across the sheet. For arranging that such a set of tests take place in sequence, a rotary switch, for instance a switch of the uni-selector type may be arranged to he stepped from one angular position to the next by the movement of the position switch from one position to another when the printing device completes the printing of a test result. This rotary switch can then be used to produce the necessary changes in the connections between the parts to be tested, for instance quads of a cable, and the testing apparatus, for instance one or more bridges.

The invention will be further described in connection with an apparatus for the automatic recording of a sequence of four tests on each of the quads of a telephone cable. In the description of the apparatus it will be assumed that it is to be used for what is known as core testing of a telephone cable, that is testing of the quads, each containing four insulated conductors, after the quads have been laid up together to form the cable but before the sheath has been applied. The apparatus is described by way of example and with reference to the accompanying drawings wherein:

Figure 1 is a block diagram illustrating the general arrangement of that part of the apparatus incorporating the main features of the invention, and

Figures 2-5 together constitute a detailing circuit diagram of the complete apparatus.

In the block diagram, Figure l, where double lines are shown connecting two pieces of apparatus the conventlon is adopted that they represent a large number of wires appropriate for the connection of the two pieces of apparatus. In all the figures a triangle at a free end of a line indicates its connection to one side of a source of direct current of which the other side is earthed. All the magnet and relay coils are directly connected to the D. C. supply and are energised bv completing the appropriate circuits to earth terminals represented by the conventional sign in the drawings. The switches are shown in the normal condition correspondlng to none of the relays and magnets being energised, and the position switch is in the first position.

The four tests to be carried out are one for withinquad capacity unbalance, one for inter-quad capacity unbalance and two for resistance unbalance, the first two by balancing a capacity bridge and the last two by balancing a resistance bridge. The tests are recorded by a modified typewriter, the carriage of which operates a position switch PS comprising a wiper PSW moved by the carriage over a fixed line of twenty-one contacts. The position switch provides one fixed contact for each recording position or space in the columns of the record. The types for printing the numerals 9 and the signs, plus and minus, can be actuated by a group of type actuating magnets TAM in addition to operation by the typewriter keys. The record of the test of each quad consists of four columns and in each column is a test reading consisting of a number preceded by a sign. The number may consist of one, two or three digits. Each set of four tests is preceded by a test of the integrity of the insulation of the wires of the quad. The result of this test is not recorded in figures but if it fails owing to faulty insulation the testing is automatically stopped with the wiper PSW on the first contact 1 of the position switch PS.

The four Wires of each of the quads to be tested are connected by hand in correct sequence to four sockets, one socket to a quad, at each end of the cable. namel ST1ST4 at the apparatus end and SB1SB4 at the other end of the cable. As the tests proceed the operators replace these quads by others in appropriate order so that there is always the appropriate number of quads available for the test and each quad of the cab fi. i subjected in turn to the set of tests. 7

The apparatus includes a rotary line switch RLS (Figure 1) controlling a group of test selection relays TSR (Figure l) by which are brought about the necessary circuit changes for selecting the quads by appropriately connecting the sockets in succession and selecting the appropriate tests for each quad. As shown in Figure 3 this switch comprises five levels RLS1-RLS5. This switch in conjunction With the test selection relays T'SR which are described in more detail hereinafter, selects the quads to be tested in sequence and provides for each of the four tests to be recorded for each quad in sequence and for the correct terminating sequence. The switch provides for the primary insulation testing of each quad and, in conjunction with a hand operated key, provides for the omission of certain tests from the normal set of four when required. The rotary line switch is moved step-by-step by a magnet TS (Figure 5). Each level of the switch comprises twenty-five fixed contacts engageable by a rotary wiper, the wipers of all levels being ganged together mechanically so that at any time all the wipers are in the same angular position. The contacts in all the levels of the rotary line switch RLS are arranged in five groups of five, the first four groups corresponding to tests on four quads in succession, and the remaining group being inoperative except in the first level RLSl where it is associated with a homing circuit for the switch.

The first level RLSl controls relays CA--CD which determine the selective connection of the test sockets to a group of six bus-bars Xl-X4, Y1 and Y2. From these bus-bars selective connections are made to the various testing circuits through the second switch level RLS2. In the normal non-operated condition shown in the drawings all the sockets ST1ST4 are connected to earth. Under testing conditions all the core terminals in one socket are connected to the four bus-bars Xl-X4 and two terminals of another socket are connected to the remaining bus-bars Y1 and Y2. The remaining socket terminals are earthed. The contacts in each group of five in switch level RLSl are permanently connected together and the first, second, third and fourth groups are connected to socket selection relays CA, CB, CC and CD respectively. When for example the wiper of this level engages any contact in the first group, relay CA can be energised to close switches CAL-CA4 to connect socket STl to bus-bars X1-X4 and switches CA5-CA6 to connect two terminals in socket ST3 to bus-bars Y1 and Y2. When all the sockets have been so connected and tested, the wiper in this level contacts the final group of five contacts to energise a homing relay CS. This connects the rotary line switch magnet TS to earth through a changeover switch CS1 and its own interrupter switch T31 (Figure 5) so that the switch homes to the starting position in which the wiper is again on the first contact. In the second level RLSZ the first contact of each group of five is connected to a relay CE which will close the switches CE1-CE4 to connect the insulation tester TS to the bus-bars X1X4. This insulation tester ES may be of the form described in the specification of our United Kingdom patent application No. 13,146/52. it tests each core in sequence and the-remaining tests cannot proceed if the insulation test reveals a faulty core. if the insulation test is satisfactory the relay DE is energised to close switch C131 and energise relay DF, associated with the first, sixth, eleventh and sixteenth contacts of the third level RLS3, which holds by the closure of switch DFll. The insulation test has been initiated by the closing of a switch DAZ following the energisation of a relay DA. This relay DA is energised by the manual closing of a group of switches KTLL KTRl, KBLI and KER When relay DF is energised at the end of the insulation test a switch DF2 opens to release relay DA.

It is convenient here to explain the procedure by which the machine operators initiate the testing operation. All the various current-and voltage supplies are switched on 2,769,958 u 6 o l by conventional arrangements. All the magnets and reand fifth positions corresponding to resistance testing lays are directly connected to a D. C. supply indicated in three relays CK, CL, and CLS are affected. Relay CK another operator at the other end of the cable. Before 10 able the resistance unbalance check measurements to be all these keys can be operated an electroma netic lock taken, and reray CLS short crrcurts at a switch group not illustrated, must be released by the closing of switch CLSl the four sockets SBl-SB4 at the far end of the CONI which is under the automatic control of the typecable. The fourth level RLSI is associated with two writer carriage. This switch CONI is closed only when control circuits, one operating as already described on the carriage is in the starting position with the position the first of each group of five contacts at the start of switch wiper PSW on the first contact. This switch comtesting and the other operating in the remaining four pletes a circuit from the first contact of each of the four positions. The other control circuit includes a relay groups of five in the fourth rotary line switch level RLS4 LM which serves to complete the c1rcu1ts necessary for apparatus operator closes, with both hands, keys KTL fifth positions of the rotary line switch. Relays CN and connection of socket STl. Switches KTLI and KTRI when it is required to cut-out some of the tests. The partially complete the circuit to relay DA, and switches effects of relays CM, CN and C0 are described below.

KTLZ and KTRZ light lamps LR1 and LR2 at reduced The capacity and resistance bridges are adjusted to the voltage. The other operator, noting from lamp LB1 balanced condition by the bridge adjusting relays BAR that the appropriate socket is connected to the correct which introduce appropriate capacity and resistance into quad at his end of the cable, closes with both hands keys the variable arms of the bridges. The voltage compara- KBL and KBR. This completes, at switches KBLI and tor VC, which is of the form described in the specification in each of the four groups in the third level RLS3, which arrests the testing operation when the balanced condition initiates the insulation test in the manner already rndris attarned and also determines whether a negative or cated At the same time switches KBL2 and KBRZ close positive value rs to be recorded The voltage comparato increase the illumination of lamps LR1 and LR2, givtor VC includes a three-position sensitive relay BA ining a visible indication that the insulation testing has corporating a three-position switch BA1. In the second begun. to fifth positions of the rotary line switch RLS the ctr- As indicated above, when the insulation test is comcuit to relay BA is closed by switch CM2. The initial pleted satisfactorily, the circuit to relay DA is opened at unbalanced condition causes BAl to move to one of its switch DF2. When relay DA was energised a switch closed positions. Relay BH is energised to close switch DAI (Figure 5) was opened in the circuit to a typewriter BHl (Figure 4) to prepare the circuits for the bridge relay CQ. This switch being now returned to the normal adjusting relays. Relay BB or BC operates, according closed position completes the circuit to relay CQ through to Whether the reading is negative or positive, and is held switch DF3, and switch CQ2 closes to earth the position by the appropriate switch BB1 or BCI. Also switch BB3 switch wiper PSW which is on the first contact. This or RG3 closes to energise relay BD, which is held at complete circuits to the stepping magnet TS for the rotary switch BDS. The relay BD, by closing at switch BDI line switch and for a relay CU which holds by closure of a circuit to relay BI sets the brid e adjusting relays in opswitch CUZ in series with switch DFI. Relay CU closes eration and also releases switch B13 so that relay BB or switch C U6 to the spacer magnet M82 which automati- BC is held only by its own switch BB1 or BCl. The

cally prints a space in the first position and causes the apparatus is normally set to print a posrtrve sign. Re-

energises relay CQ and opens switch CQ2 to break the cuit at switch BB6 from printing circuit to the wiper PSW. The circuit to the stepping ing magnet M. When balance magnet TS being also broken the rotary line switch steps position switch BA to the second position. This movement releases relay DP, opening switch DFI to release relay CU and open the associated switches. adjusting relay group BAR by opening switch BH 1. Re- The remaining relays associated with the second rotary lay BE, if operated, remains held by its own switch BEI, lrne switch level RLS2 operate as follows. Relay CF in as does relay BD by its switch BD5.

the second position connects the capacitor bridge to the The capacity bridge is balanced by successively switchbus-bars X1-X4 through the switches CF1CF4 for ing in to the adjustable arm a number of capacitors the purpose of the side-to-side tests. In the third posiwhich are added in steps by swrtches A3I4, K4, L4- tron relay CG connects the bus-bars X1, X2, Y1 and Y2 S4 and T7 until balance magnet M+ to printis achieved, the three- 1 is brought to the centre zero posiis reached The bridge 18 norto the capacitor bridge for the pair-to-pair test. In the mally connected to grve positive readings but is altered fourth and fifth positions the relays CH and CI connect to give negative readings by opening switch BB2 and the appropriate bus-bars to the resistance bridge through changing over switch BB3. The resistance bridge is balthe two switch groups CH1-CH3 and CI1CI3 in see anced by successively short-circuiting a series of resistquence. The third level RLS3 operates in the first poances in the adjustable arm by means of switches A4- sition in the manner already explarned in connection with H4 and 15. This bridg the insulation test. In the second and third positions, "0 tive reading by changing over switch BES,

opening BB4 corresponding to capacity testing, relay CI is energized. and closing BE7. The bridge adjusting relay roup BAR This connects to the capacitor bridge a voltage comparacomprises the following relays. Relays A-I, the unit tor VC at switches C11 and CJ2 and an oscillator OS at relays switches C13 and C14. The voltage comparator will be time to a maximum of nine by operating switches A3 referred to in more detail hereinafter. In the fourth I4 in the capacity bridge and A4-I5 in the resistance bridge.

the resistance bridge is equivalent to altering the value of the resistance arm by 0.1%.

relays. Relay K at switchK4 adds 100 pf. to the ate circuits to transfer the required and that V tens relay L and also prepares Each unit'is l pf. in the capacity bridge and in Relays K-S are the tens capacity bridge or at switches K and K7 alters the resistance bridge by 1.0%. Relays L-S each add 100 pf. to the required arm of the capacity bridge at switches L444.

A Relay T is the hundreds relay and adds a 1,000 pf. to the "capacity bridge at switch T7. operate during resistance testing. Some of these relays have otherfunctions.

The relays L-T do not Relays AI, and I l-T prepare the appropriate circuits for the operation of the type actuating magnets TAM. Certain of the relays prepare the circuits for operating'the next relay so that the system is self-running. Relays K and T also set the approprisign to another column if required, so that'the sign is always printed directly before i the first significant figure in the record.

The I group of bridge adjusting relays, IIE, effect the transference of circuits from one of the other groups to the succeeding group. Relay IE operates differently from the others in that it is .an excess value relay serving to stop the apparatus if a value in excess of the range of the machine is encountered. Relays I-IC efiect the transference from the units relays to the tens relays, ensure that the units relays are released when the tens relays operate at appropriate times. Relay ID operates in conjunction with relay I to release all the units and tens relays and replace them with the hundred relay T when the appropriate value is reached.

The units, tens and hundred relays are energised by switches controlled directly or indirectly by previous relays so that the balancing operations proceed continuously until stopped automatically at balance. The first units relay A is energised by closure of switch Ell from relay BI and this closes switch A2 in the operating circuit of the next relay E. This is repeated until the ninth units relay I is energised when a somewhat different operation occur. The units relays are held by their own switches Al-Il to a holding line earthed through switch I5. At balance, switch BHIi opens to stop the operation of the relays, but those already energised remain operated by their holding switches. The relay I indirectly prepares the circuit for the first tens relay K. The relay I closes switch 13 to energise the transferring relay I, which holds at switch I2 and opens switch I 5 to release the holding circuits for all the relays A-I. The tens relays are arranged in two groups, the upper group as shown in Figure number relays K--S and the lower group containing the even number relays L-R. The selection of the appropriate relay groups is efiected by two-way switch IE6 controlled by the relay IE. In the normal condition switch I 36 is set for relay K to be energised. When relay I is operated, and relay I thereby released, switches I1 and 12 complete a circuit through switch I B6 to relay IA and the first tens relays K. Switch IAll closes to energise relay IB which holds by switch IE3. Relay K holds by closing switch KI and switch K2 closes to prepare the circuit for the next tens relay L in the lower group. Relay IA has held at switch IA2 and released relay I at switch IAo. Relay IB releases relay IA by opening switch IE3, moves switch IE6 to the offnormal position to prepare the circuit for the second the circuit for relay IC by closing switch IE2. It will be een that after one of the tens relays K, M, O, Q and S of the upper group has operated the relay IE is held so that switch IE6 is in the appropriate position for operation of one of the lower group of tens relays L, N, I and R, and switch IE2 -is closed to prepare the circuit to relay IC. It will also be seen that relays IA and IC function alternately. When'the conditions are such that the second tens relay L requires to be #energised, relays- I and I 4 including the odd position. are earthed through switch ID3 and relay ID is used last of the tens relays '8: before but relay-1C is energised in place of In this case relay I is released by the openoperate asrelay IA.

ing of switchICS and, switch IC6 having also opened,

relay IE releases when switch I6 returns to normal. Relay IC is released by the opening of switch IE2 and a circuit for the next tens relay M in the upper group is prepared by the movement of IE6 to the normal The holding circuits for the tens relays K-S to release all these relays when the hundred relay T operates. The circuit to relay ID is prepared when the S operates to close switch S3. It will be seen that switch IE6 has already been brought to the off-normal position but this does not afiect relay T. When relay I next operates the closure of switch energises relay ID while relay I is energised in the usual manner. Switch IDS opens to release all the tens relays KS while relay I is releasing all the units relay A-I. Switch ID6 also opens to prevent the operation of any of the relays L, N, P and R when relay I releases to reclose switch I2. The hundreds relay T is energised by switch IDl and holds by switch T1. The relay T is sufficiently slow in action to ensure that it will not open switches T3 and T4 in the operating and holding circuits of relay ID until all the tens relays have cleared. When relay ID is released switch ID6 closes to energise relay IC through oir' normal switch IE6. This releases relay I by opening switch JCS and relay IB is released by switch I6 going to normal and switch IC6 opening. Switch IE6 thus returns to normal to prepare the circuit for the next tens relay K and relay] C is released by the opening of switch I B2. When the value established by the bridge adjusting relays has been recorded, they are all released by the opening of switch CU1 as afterwards described.

When the value to be measured is in excess of that for which the apparatus is designed to measure the operation is automatically stopped. At the maximum value which can be measured relays S and T are energised at the same time and prepare a circuit to the excess value relay IE by closing two switches S2 and T2. At this stage switch IE6 is in the off-normal position. When relay I next operates the effect of closing switch II will be to energise relay IE, which is held by switch IE1 and brings the apparatus to rest by breaking the earth circuits at switches IE2 and IE3. The condition is now restored manually and relay IE released by manually opening switch K0 in its holding circuit.

The group of type operating magnets TAM comprises two space magnets M31 and M82, the sign magnets M+ and M- and the digit printing magnets MtlM9. Numbers I, 5, II, 16 and 21 of the position switch contacts are connected together to energise relay CU and print a space over magnet M32 as already explained when switch (116 closes. In all these positions except the first relay CU opens switch CUI to release all the bridge adjusting relays at the end of a recording. Also switch CUS connected between contacts 2, '7, i2 and I7 and the type actuating magnets prevents premature operation of these magnets as the position wiper ESW moves on to these contacts. Contacts 5, l0, l5 and 20 are normally connected to print any value from 09 according to the setting of the units relay switches A6I6. Contacts 4, 9, 14. and 19 are normally connected to print a sign dependent upon the position of switch BB6. When the record contains two significant figures, the tens relay K has moved switch K3 into the off-normal position to connect these contacts to the group of magnets M1M9, and the appropriate magnet is selected by the tens relay switches LS-R3 and S6. A cipher will be required in this position only when relay T has operated and no tens relay is operated; under these circumstances the magnet M0 is connected over switches T8 and K6. Contacts 3, 8, l3 and 18 are normally connected over switches T6 and K8 to the space magnet MSI. When there are two significant figures in the'record these contacts are conhected to one of the sign magnets by switch K8 off-normal and when there are three significant figures the operation of the hundred relay switch T6 connects these contacts to the digit magnet M1. The remaining contacts 2, 7, 12 and 17 are also connected together and, normally, to a space magnet MSI by switch T5. When the record contains three significant figures the hundred relay switch T ofi-normal connects them to the circuit for the sign magnets M and M The following description indicates the successive steps in the operation of the apparatus in the testing of four quads connected to the terminal sockets ST1fiST4. In the first position of the rotary line switch RLS the first quad is connected. The position switch wiper PSW is on contact 1 of the position switch and the insulation test is carried out resulting in the operation of relay DE. This causes the operation of the typewriter relays CQ and CU. The rotary line switch RLS is moved forward one step by its magnet TS, and the spacer magnet M52 moves the typewriter carriage to carry the position switch wiper PSW to contact 2. The capacity bridge is brought into circuit by relay CF from the rotary line switch level RLSZ and the balancing operation is initiated by relay CM from the rotary line switch level RLS4. Switch EH1 closes in the operating circuit for the bridge adjusting relays BAR which balance the bridge in the manner already described, selecting the appropriate type actuating magnets TAM. When balance is attained, switch BHI opens and the bridge adjusting relays are held in the operated position. Switches BB7 and BC6 having returned to normal and relay BD being held to close switch BD6, the typewriter relay CQ is i e-energised to close switch CQ2. A printing circuit is thus completed through the wiper PSW and contact 2 of the position switch to the selected type actuating magnet. The typewriter is moved automatically step-by-step by the usual mechanism into the position corresponding to position switch contacts 3, 4, 5 and 6, operating a magnet in each position. In the sixth position, relay CU is again energised since switch B12 is closed by relay BI which itself held by relay BD through switch BB1. Relay CM is now released by switch CU4, the bridge adjusting relays BAR are released by switch CUl and the spacing magnet M82 is operated by switch CUG. At the same time the magnet TS steps the rotary line switch RLS into the next position to energise relay CG from level RLS2. The apparatus now proceeds with the next test, the position switch being on contact 7. These operations are continued until all the tests have been made and recorded and the position switch wiper PSW is on the final contact 21. Again a space is printed by magnet M82 and the magnet TS steps the rotary line switch to the sixth position while the typewriter carriage is returned by hand or automatically to the initial position with the position switch wiper on contact 1. Unless the position switch is so returned, switch CONl will remain open and testing cannot be recommended. From the rotary line switch level RLSl the next quad is connected for test by the relay CB. The sets of tests are repeated successively as the rotary line switch energises the two remaining quad connecting relays CC and CD, until the position switch wiper PSW engages contact 21 for the fourth time. The rotary line switch RLS now moves to the twenty-first position to energise the homing relay CS from the first level RLSl. This alters switch CS1 to provide a homing circuit to the magnet TS which returns the switch RLS to the first position. The operators having appropriately connected new quads to the sockets ST1ST4 and SBlfiSB4, the complete cycle of tests is repeated automatically and this repetition continues as long as the quads are correctly connected and no other conditions occur to arrest the operation.

If at the beginning of a test a bridge is balanced, that is the value to be recorded is zero, the relay BH will not operate because the three position switch BAl remains in the central open circuit position. Switch BHl in the bridge adjusting relay operating circuit will not be close To check that a true balance exists and that this condition is not due to a fault, a capacity-slugged relay BF operates after a short interval from the closing of switch CMS to add a small capacity or resistance to one arm of the appropriate bridge. The resulting bridge unbalance is caused to operate the relay BA for starting the bridge testing but a value zero will be printed since the bridge adjusting relays will not function. The relay BF adds capacity to the positive side of the closing switch BB3 or, by closing switch BF4, positively alters the balance of the resistance bridge. At the same time switch BFl operates relay BG which opens switch BGZ in the circuit to the bridge adjusting relay A to prevent this and associated relays operating when switch BI1 eventually closes. The positive alteration of either bridge causes switch BAl to move to the positive position to operate relays BH and BC. Relay BH is ineffective but relay C starts the initial testing procedure by closing switch RC3 in the circuit to relay BD. This releases relay BF by opening switch BB3 and the bridge is returned to balance. This returns switch BAl to the central position to release relay BC. The typewriter therefore prints a cipher because relay CQ is energised through the normally closed switch RC6 and the switch BB6 which has been closed by the relay ED. The relays BG, BD and BI are released as before by the opening of switch CUI. It will be seen that a Zero reading is always preceded by a positive sign.

Arrangements are provided for eliminating either the insulation resistance test and the two capacity tests or the two resistance tests. For making the necessary circuit alterations there are provided two switch groups S/S and Cu mechanically coupled for manual operation. In one position the Cu group is operated for eliminating the first three tests and in the other position the 8/8 group is operated to eliminate the last two tests. In the first condition no testing takes place in the first three positions of the rotary line switch RLS. Switch C113 interrupts the earth connection to the second and third levels RLS2-RLS3 of the rotary line switch and switch C114 prevents the normal operation of the relay CM which normally initiates the bridge balancing operations in the second to fifth positions of the fourth level RLS4. Switch Cu2 closes to prepare a circuit to a relay CO from the first to third positions of level RLSS, and switch Cul prepares a circuit to relay CN from the fourth and fifth positions of that level. At the beginning of the tests the manual closing of switch KTL3 operates relay CO which holds by switch CO6. This relay sets switches COl-CO4 relay CO from the fifth level RLSS and return all the CO group of switches to normal. From this level relay CN is operated, closing switch CN2 to restore the earth connection to the rotary line switch levels RLS2 RLS3 In the second condition no testing is to be carried out in the fourth and fifth positions of the switch levels RLS3RLS4 are broken by switches 8/31 and 5/84 respectively. Relay CN is operated in the first to third positions of the rotary line switch by switch 8/82 and relay CO in the fourth and fifth positions by switch S/S3. It will be seen that the operation of relays CN and CO in the reverse order to that already described, but in the same manner, will produce the required result.

record sheet, comprising nomination groups In order to check the operation of the apparatus a switch KS1 is closed manually to operate a relay CP which by closing the switch group CP1-CP6 connects to the busbars X1-Y2 a circuit network STD simulating a standard cable.

What we claim as our invention is:

1. Apparatus for automatically obtaining and printing the reading of an instrument or a group of instruments and for printing successive readings as columns of figures on a record sheet, comprising a record sheet carrier, means for producing relative step-by-step movement between the carrier and a printing position, a number of type-actuating electro-magnets, a cascade of relays for selecting circuits through the electro-magnets, means responsive toeach instrument reading for actuating the relays to prepare the circuits to the type-actuating electromagncts appropriate for that reading, a position switch operatively connected with and actuated by the relative step-by-step movement of the carrier, circuits to the electro-magnets for selection by the position switch according to the position of the carrier, and means for interrelating the circuits established by the cascade of relays with the circuits established in an associated position of the position switch to actuate the appropriate electro-magnets to print a part of the reading.

2. Apparatus for automatically altering the impedance of a measuring circuit to balance the circuit in a succession of tests and for printing the values of the impedance alterations for successive tests as columns of figures on a a number of type-operating electro-magnets, a record sheet carrier, means for producing relative step-by-step movement between the carrier and a printing position, a set of relays arranged to act 1 in sequence to alter the impedance in steps until balance is obtained, means for preparing through the relays at balance electro-magnet circuits appropriate for printing the value of the impedance alteration, a position switch operatively connected with and actuated by the relative step-by-step movement of the carrier, circuits to the electro-magnets for selection by the position switch according to the position of the carrier, and means for interrelating the circuits established at the balance setting of the relays and at the associated position of the position switch to actuate the appropriate electro-magnets to print a part of the record of the value.

3. Apparatus as claimed in claim 2, including holding means for retaining the setting of the relays until the impedance value is printed and means actuated by the movement of the position switch for then restoring the-relays to the starting condition.

4. Apparatus as claimed in claim 2, in which the relays include units, tens and hundreds groups, and transfer relays for initiating the operation of the two higher deafter the operation of all the relays in the next lower denomination group. and for returning all the relays in the lower denomination group to their initial positions.

5. Apparatus for automatically altering the impedance of a measuring circuit to balance the circuit in a succession of tests and for printing the values of the impedance alterations for successive tests as columns of figures on a record sheet, comprising a number of type-operating electro-magnets, a record-sheet carrier movable step-by-step relative to and through a printing position, a position switch operatively connected to the carrier to establish circuits determined by the position of the carrier, a set of relays arranged to operate in sequence to alter the impedance in steps until balance is obtained, means for preparing through the relays at balance electro-magnet circuits appropriate for printing the value of the impedance alteration, an operating circuit and a holding circuit for the relays, a circuit responsive to the condition of the circuit to be balanced for interrupting the relay operating circuit at balance, means for interrelating the circuits established at balance by the relays and by the associated position of the position switch to actuate the appropriate electro-magnets to print a part of the record of the value and means controlled by the position switch for releasing the relay holding circuit.

6. Apparatus for automatically altering the impedance of a measuring circuit to balance the circuit in each of a series of tests in succession and for printing the values of the impedance alterations for successive tests as columns of figures on a record sheet, comprising a number of type-operating electro-rnagnets, a record-sheet carrier movable step-by-step relative to and through a printing position, a position switch operatively connected with the carrier to establish circuits determined by the position of the carrier, 21 set of relays arranged to operate in sequence to alter the impedance in steps until balance is obtained, means for preparing through the relays at balance electromagnet circuits appropriate for printing the value of the alteration, means for interrelating the circuits established by the relays at balance and circuits established by the associated position of the position switch to actuate the appropriate electro-magnets to print a part of the record of the alteration, a test-selection-switch movable step-bystep for preparing the circuits to be tested and means actuated by the movement of the position switch at the recording of each test to move the test-selection-switch into position for the establishment of the next test.

7. Apparatus as claimed in claim 6, including means for balancing a capacity bridge and a resistance bridge in sequence, the relays being effective to alter capacitance and resistance in the appropriate bridge and the testsequence-switch being adapted to establish the appropriate connections between the bridges and the relays.

8. Apparatus for automatically determining the impedance of each of a group of circuits by subjecting each circuit in turn to a series of impedance bridge tests and for printing the bridge readings for successive tests in each series as a column of figures on a record sheet and as separate lines for the separate circuits of the group, comprising a number of type-operating electro-magnets, a record-sheet carrier movable step-by-step relative to and through a printing position, a position switch operatively connected to the carrier to establish circuits determined by the position of the carrier, a set of relays arranged to operate in sequence to alter the bridge impedance in steps until balance is obtained, means for establishing through the relays at balance electro-magnet circuits appropriate for printing the value of the alteration, means for interrelating the circuits established by the relays at balance and circuits established by the associated position of the position switch to actuate the appropriate electro-magnets to print a part of the record of the impedance alteration, a test-sequence-switch movable step-by-step for preparing the circuits in sequence for testing each circuit in the group and for each test in each series, means actuated by the position switch at the recording of each test for moving the test-selection switch into position for establishing the next test and also means actuated by the position switch for returning the carrier to the initial position for recording another line of figures at the end of each series of tests.

References (Cited in the file of this patent UNITED STATES PATENTS 

